1. Field of the Invention
The invention relates to a polymer treating method and a polymer treating apparatus that a polymer is processed into thermoplastic resin or wax by denaturalization or decomposition, or by cutting the cross-link point or molecular chain of cross-linked polymer, and more particularly to a polymer treating method and a polymer treating apparatus that a polymer is reacted with a reaction agent in supercritical state by using an extruder.
2. Description of the Related Art
In recent years, as environment problems become important, the cost in disposal of wastage tends to increase. Regeneration or recycle of polymer is also desired. In this trend, the material recycle of thermoplastic resin is developed since it is possible to mold the thermoplastic resin again by using the fluidization property obtained by heating.
However, a thermosetting resin, a cross-linked polymer, rubber etc. are difficult to apply to the material recycling since the fluidization property thereof cannot be obtained even by heating due to the molecular three-dimensional network. Therefore, although the thermal recycling thereof is somewhat done, they are mostly discarded as landfill waste etc.
A technique is researched that realizes the material recycle of thermosetting resin or cross-linked polymer. For example, proposed are a method of processing a polymer into thermoplastic resin by deforming the molecular three-dimensional network structure to recycle it, and a method of making low-molecular substance (wax substance) by cutting the principal chain of a polymer to reuse it as an additive.
In order to put such a method into practical use, a means for treating the polymer continuously is required. Extruders are suitable for that purpose. Heat and pressure conditions required in processing a stable thermosetting resin or cross-linked polymer into thermoplastic resin by deforming the molecular three-dimensional network structure can be easily satisfied by the extruders. Those in making a wax substance can be easily satisfied thereby as well. Also, in making the thermoplastic resin, a thermosetting resin or other agent can be easily added to the thermosetting resin or cross-linked polymer by using the extruder.
Japanese patent application laid-open No. 2001-253967 (prior art 1) discloses a method that cross-linked polyethylene and water are supplied into an extruder, and are processed into a thermoplastic material by extruding under conditions to make water to be supercritical or semi-critical in the extruder, i.e., at a temperature of 200 to 1000° C. and a pressure of 2 to 100 MPa.
Japanese patent application laid-open No. 2002-249618 (prior art 2) discloses a method that a cross-linked polymer is introduced with a high-temperature and pressure fluid into a reaction vessel to generate a reacted substance, the reacted substance is introduced into a separator to be separated from the high-temperature fluid, and the reacted substance is extruded by the extruder.
In prior art 1, water serves as a reaction agent to process the thermosetting resin or cross-linked polymer into the thermoplastic material under the chemical reaction. However, prior art 1 does not disclose an effective means for separating the thermoplastic material after mixing the reaction agent with the thermosetting resin.
In prior art 2, a separation bath is used to separate the polymer from gas after mixing the reaction agent with the thermosetting resin. However, since the extruder of prior art 2 has to be disposed spatially, the manufacturing cost of apparatus increases. Further, if the polymer generated sticks to the wall of separation bath, it is difficult to supply the polymer into the degassing extruder.